中文摘要：

为了进一步了解丛枝菌根（AM）真菌群落对不同海拔环境的响应,基于孢子形态学鉴定,研究了西藏高原不同海拔区域主要草本植物AM真菌的群落特征、菌根侵染及其变化.结果表明：藏东南低海拔区（2200-3400 m）、藏中中海拔区（3400-3900 m）和藏北高海拔区（4300-5300 m）的AM真菌分别为11属31种、11属20种和6属14种.随着海拔上升,孢子密度（r=0.978,P〈0.01）、物种丰度（r=0.462,P〉0.05）均趋提高,优势种、特有种比例大幅增加,Shannon指数（r=-0.945,P〈0.01）极显著下降.不同海拔区之间AM真菌群落Sorensen相似性系数（0.526-0.592）较为接近,仅在总体上随海拔差异扩大略趋下降;藏东南低海拔区、藏北高海拔区菌根侵染率无显著差异,但均显著低于藏中中海拔区.各海拔区内,不同海拔梯度对AM真菌群落、根系侵染亦具显著影响,但影响程度、影响趋势因整体海拔环境不同而异.说明西藏高原AM真菌群落趋于生境选择,受控于海拔所主导的水热环境及土壤环境.

英文摘要：

The community structure of arbuscular mycorrhizal fungi（ AMF） and mycorrhizal infection in the main herbaceous plants were studied along the elevational gradients on the Tibetan Plateau,and AMF community was characterized based on spore morphology. Community of AMF at lower elevations（ 2200- 3400 m） in southeast Tibetan Plateau included 11 genera,covering 31 species,whereas AMF at intermediate elevations（ 3400-3900 m） in central Tibet included 11 genera,covering 20 species,and that at higher elevations（ 4300-5300 m） in northern Tibet included6 genera,covering 14 species. With the increase of elevation,both spore density（ r = 0. 978,P〈0.01） and species abundance（ r = 0.462,P〉0.05） tended to increase. The proportion of dominant species and endemic species increased substantially,while the Shannon index（ r =-0.945,P〈0.01） decreased significantly. There was no significant difference in Sorensen index（ 0. 526-0.592） among different altitudes. Mycorrhizal infection at intermediate elevations was significantly higher than that at lower elevations or higher elevations,while the latter two did not differ significantly. Within an altitude range,elevation had significant influence on AMF community and mycorrhizal infection,and the effect differed among the three elevational sites. The results demonstrated that AMF community on the Tibetan Plateau tends to be habitat specific. The water and thermal environment as well as soil environment are the driving forces for shaping AMF community assemblages.